Project Design for TAPR Manufacturing Design for ... · TAPR Manufacturing Design for...

© 2010 Scotty Cowling WA2DFI© 2010 Scotty Cowling WA2DFI

Project Design for Project Design for TAPR ManufacturingTAPR Manufacturing

Design for Manufacturability-or-

How to ease your project into mass production with the least amount of pain(both yours and TAPR’s)

Scotty Cowling, WA2DFI2010 Dayton Hamvention TAPR Forum


Who Cares About This?Who Cares About This?

Anyone who…Wants to build more than one or twoWants these many copies to actually workMake the best use of limited manufacturing resources

Because…One on your bench that doesn’t work is a “Project”500 in inventory that don’t work is a nightmarePoor use of resources might mean it never gets built


Process Yields ResultsProcess Yields Results

We follow a process because it…Reduces time to marketEliminates errorsIncreases the manufacturing yieldIncreases the probability of success


Process Yields ResultsProcess Yields ResultsWe follow a process because it…

Reduces time to market (FASTER)Eliminates errors (BETTER)Increases the manufacturing yield (CHEAPER)Increases the probability of success (SURVIVAL)


Process Yields ResultsProcess Yields ResultsAnd Because we want the following benefits:

Lower the total cost of productionGet many boards in people’s handsAdvance the state of the art (especially with OHL)Have fun in the process!!!


Process Yields ResultsProcess Yields Results

Not all Process is created equal…

We want GOODProcess


Project Flow TrinityProject Flow Trinity

CONCEPT DESIGN MANUFACTURING

BLUEPRINTSPECIFICATION

Process becomes more important as we move to the right

Project flow through the three phases from idea to the shelf


Concept PhaseConcept PhaseConcept stage input: Initial Idea

Discussion/peer reviewExperimentation (use modified existing boards)Proof of conceptPartial or sectional prototype (use evaluation boards)Formalization of assumptions and functionalityFinal peer reviewVery iterative

Concept stage output: Product Specification


Design PhaseDesign PhaseDesign stage input: Product Specification

Hardware design (schematic capture)Peer reviewPCB design (layout and routing) and review (not peer)Prototype (Alpha) buildDesign validation (extensive testing) Iterative, typically 2 to 3 diminishing cycles

Design stage output: Gerber, BOM, schematic files


Manufacturing PhaseManufacturing PhaseManufacturing stage input: Gerber, BOM, schematic files

Cost out BOM, determine parts availability, set sale priceAssemble documentation packageSchedule assemblyProcure parts and PCB (may also require scheduling)Assemble and inspect PCBs (by machine and by hand)Develop test procedure and build test fixtureFinal inspect, program, test, bulk package for shipment

Manufacturing stage output: Built and tested product


Project Flow TrinityProject Flow Trinity

CONCEPT DESIGN MANUFACTURING

BLUEPRINTSPECIFICATION

The more complete and accurate the Blueprint, the easier the transition to the Manufacturing Phase will be

Project flow through the three phases from idea to the shelf


Blueprint TrinityBlueprint Trinity

1. Schematic/Netlist2. Bill-of-Material (BOM)3. Layout (Gerber) data


Schematic Schematic isis the Design!the Design!

Use a standard schematic tool

Follow simple schematic rules

Draw the schematic simply, clearly and uncluttered

Include all part information in the schematic

Include some layout information in the schematic

Create a Fab Notes document to ease PCB fabrication


Standard Schematic ToolsStandard Schematic Tools

Cadence OrCAD Capture (Windows)$1500+ per seat AMSAT has shared OrCAD licenses available free to developers

KiCAD (Linux, Windows)Open source (GPL), free license

gEDA (Linux)Open Source (GPL), free license

CadSoft Eagle (Linux, Widows, Mac)$50 (light) - $250 (std) - $500 (pro)


Simple Schematic RulesSimple Schematic Rules

Only one off-page connector for each unique signal per page

Off-page connectors should be at sheet edges, not buried within sheet

Off-page connectors should indicate signal direction, if possible

Use inter-sheet references on all off-page connectors, if possible


Draw Simply and ClearlyDraw Simply and Clearly

All instances of a signal on the same page must connect with a wire

Use more and/or larger sheets

Use a page size no more than one size bigger than your printable size

Typically “C” for a “B” size printer or “B” for a letter-size printer

A=8.5”x11”, B=11”x17”, C=17”x22”, D=22”x34”, E=34”x44”


Include Part InformationInclude Part Information

Reference designator (R3, C6, U10)

Part value (10K, 22uF, EP3C40)

Part manufacturer (Rohm, AVX, Altera)

Manufacturer part number (EP3C40Q240C8N)

Vendor (Digi-Key, Mouser, Arrow)

Vendor part number (544-2551-ND)

PCB footprint (0603, EIA-B, PQFP240)


Include Include MoreMore Part InformationPart Information

Capacitorsvoltagetolerancedielectric type/temperature coefficient

Resistorspowertype, if special

ToroidsDon’t use toroids

Other partswhatever ratings are critical to the design


BOM FormattingBOM Formatting

Group parts:

One line per part type

NOT one line per reference designator

Include part data

manufacturer and manufacturer part number

vendor and vendor part number

Include package type and/or size

Additional fields (tolerance, power, etc) needed on schematic only


Optional PartsOptional Parts

Why Do This?

Manufacturing variants

Optional functionality

Test and/or debug circuitry

Future cost reduction


Optional PartsOptional Parts

Optional parts should contain all part data fields

Add “DNI-” prefix to part value field

e.g., “10K” becomes “DNI-10K”

Note that “DNI” now appears in both BOM and Schematic


Include Layout InformationInclude Layout Information

PCB footprint (obviously)Flag critical nets with text notes in schematic

Power, timing, termination, routing

Group componentsby circuit function (add notes for proximity information)by physical proximity in layout

Switch and Jumper functionsJumper settings are especially helpfulLabels for silk screen (SS_DESCSS_DESC property)


Check for Common ErrorsCheck for Common Errors

Schematic Netlist Checking

Check for netlist errors before going to layoutAutomatic schematic checking

Run DRC from your schematic tool

Manual checkingDuplicate and/or shorted power buses (“5.0V” ≠≠≠≠ “5V”)Similar, but not identical, net names (“data-in” ≠≠≠≠ “data_in”)Single node nets (DRC normally catches this)


Check for Common ErrorsCheck for Common ErrorsLayout (Gerber File) Checking

Automatic Gerber file checkingRun DRC from your layout toolMany PCB shops provide free on-line DRC service

Manual CheckingCheck EVERY polarized component (LEDs, caps, Zeners, etc)Check EVERY connector and header for proper pin 1 orientationCheck EVERY connector for proper pin order (reverse/mirror)Check EVERY plane layer (many are placed manually)Double check EVERY power connector for proper polarity


Check for Common ErrorsCheck for Common ErrorsLayout (Gerber File) Checking, cont’d

PDF files are useful, but…

Free Gerber viewers are readily available (Win and Linux)GC Prevue is standardlist of others here:

http://www.mitsi.com/PCB/free%20viewers.htm

Note that layout errors may not show up on the schematicSilk screen data is almost always generated manuallyAn incorrect silk screen can cause assembly errors


Create Fabrication NotesCreate Fabrication Notes

PCB material (FR4)

Copper thickness (1 oz/ft2)

Layer stack up (order)

PCB dimensions (100mm x 120mm)

Designer contact info


Sample Sample FabFab Notes FileNotes File


SummarySummary

To release to manufacturing, you need:

At least three fully tested Alpha PCBsFully annotated schematicComplete BOM (no TBDs or missing part data)Gerber filesClean DRC on schematic and Gerber filesFab Notes file


TAPR Can Help With FundsTAPR Can Help With Funds

Because

You put in your time and expertiseCommunity peer reviews give early feedbackHardware is expensive

Designers should not have to both bear the cost and donate their time


Thank you!Kit Information At:

www.tapr.org

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